i2c hang

[Barney]

I am using CCS 3.212 with the Microchip IDE & ICD-2. I am trying to talk to a AD7416 temperature sensor using a 16F87 PIC and I2C. I am getting hung up in call to an initialization routine to setup the AD7416. I turn on a LED before (A0) and another LED (A1) after the call. The first LED comes on, the second does not. If I comment out the call to init_i2c(), then both LEDs come on.

I have tried this both in ICD2 debug mode and non-debug (ICSP) and get the same thing. If I remove the ICD2 and reset the PIC, again the same thing. In debug mode, I watched it loop endlessly in a portion of the code generated for the #use i2c statement.

This seems pretty simple, I don't see what I am doing wrong. Reading the prior posts, apparently there has been issues with the I2C complier code in the past. Any ideas?

Thanks
Barney


#include <16F87.h>
#fuses NOWDT, NOPROTECT, NOLVP, INTRC_IO
#use delay(clock=8000000)
#use standard_io(A)
#use standard_io(B)
#use i2c(master, sda=PIN_B1, scl=PIN_B4)
//B1 = SSP I2C SDA, B4 = SSP I2C SCL

void init_i2c();

void main(){
disable_interrupts(GLOBAL);
output_bit(PIN_A0, 1);
init_i2c(); //initialize i2c addr 0
output_bit(PIN_A1, 1);
}


void init_i2c(){
//set pointer register for temperature register
i2c_start();
i2c_write(0x90); //address & write cmd
i2c_write(0); //set ptr reg to 0 (temperature)
i2c_stop();
}

[Mark]

Did ya put pullups on the I2C lines?

[Guest]

Doh! Put on the 1K pull up resistors and it worked like a champ!

Thanks

[Haplo]

For a 5v system it is uaually recommended to use pull-ups biger than 1.6K. I always use 3.9k and have never had any problems.